London’s Royal Opera House, with the help of modern technology, has been projecting live performances to big screens in outdoor public spaces around the country.

Early this week I went along with family to Bristol’s Millennium Square to see a free live screening of Verdi’s historic opera Simon Boccanegra, which promised, said the local press, ‘an unexpected reunion between a father and his long lost daughter, a passionate love affair and a murderous plot’. Further, we were told, ‘opera buffs turning up will find deck chairs, Astroturf, ice creams and summer-inspired food on offer for a fun, “picnic-in-the-park” feel.’

Despite louring clouds on the day, we arrived to find plenty of people – more than could be seated on the provided deck chairs – and ten foot square of Astroturf quite dwarfed by the gathered audience, let alone the Millennium Square itself. And to warm us all up was a rock band I’d never heard of.

I admit to feeling relief when the ROH relay started, except the sound-system initially kicked in at a volume which well-matched that of the preceding band. But soon we were engrossed in the spectacle of the production – at its most magnificent when presenting the Doge's council chamber in the final scene of Act I – and by the story movingly presented both by Verdi’s music, conducted by Antonio Pappano, and the very fine cast.

In the title role was the main star of the evening, Plácido Domingo, who quickly riveted attention with his still glorious voice and superb acting. At first I feared less seasoned members of the audience might have their prejudices about opera reinforced by the Prologue, musically magnificent but largely populated by, shall we say, venerable singers of substantial girth.

But this evaporated with the start of Act I and the appearance of Amelia. She was sung by Marina Poplavskaya, looking every inch the youthful and innocent lost daughter capable of stirring feelings both in her father and her would-be suitors, who include her lover Gabriele Adorno, the young tenor role sung by Joseph Calleja.

A potential blot on the evening was the indisposition of Ferruccio Furlanetto, in the role of Boccanegra’s foe Fiesco. He appeared, but miming to English bass John Tomlinson’s singing from the wings. Inevitably the close-up camerawork highlighted the mismatch between voice and Furlanetto’s lip miming, but better that than Tomlinson, who’d been recruited only hours before the evening’s show, hampering what was evidently a well-choreographed production.

In fact, to judge from the grumblings of another blogger who had a seat in the House itself, the al fresco audience probably got the better deal since as heard in Millennium Square Tomlinson's voice appeared well-balanced with the rest of the cast.

No, I wouldn’t sacrifice the chance of visiting the House, nor any of Britain’s top opera venues, in preference to this al fresco experience. On the other hand, after having earlier this year shared space at Glyndebourne with a bored man who rustled his sweet papers during the tensest moments of Britten's Billy Budd, I think there's a lot to be said for watching opera with an audience who clearly wanted to be there, who unselfconsciously applauded fine singing even as they knew the singers couldn’t hear them.

So three cheers to the tenor Joseph Calleja who said to the camera afterwards: ‘Our real audience is outside, enjoying the opera even in the rain.'